I´ve lost my IMEI because i deleted my efs folder from the root folder of my phone (galaxy s3) and i had no backup. Someone restored the IMEI with Zbox or Octopusbox (not sure which one it was) and everything worked fine. So i made an efs backup and flashed Cyanogenmod, but after flashing the Rom my IMEI was lost again (0049...) and the phone couldnt find a network. Restoring the efs backup did not work and so i had to go back to stock and let the guy restore the IMEI again.
And here comes my question: I am currently on stock rom with rooted kernel (havent flashed any rom since the second restore because i dont want to risk losing the IMEI again) and i really like to change the Rom because you know stock rom is kinda bad. Does anyone have a clue what i need to look out for or why my IMEI gets corrupted on flashing another Rom?